The present invention relates to an ignition system for internal combustion engines which includes a plurality of power transistors for interrupting the primary current in an ignition coil.
Known ignition systems of the above type are so designed that the primary current flowing to each power transistor is detected by the associated primary current detecting resistor so that the power transistors are controlled independently of each other by the associated current control circuits and the ignition coil primary current flowing to the power transistors is feedback controlled.
The known system of the above type is disadvantageous in that the primary current detecting resistors and the current control circuits must be the same in number as the power transistors with the resulting complication of the circuitry and increase in the cost, and moreover, the variations in primary current controlling characteristics among the primary current detecting resistors as well as the current control circuits result in the variations in primary current control among the respective power transistors.